Investment in Securities (Maturities of Securities) (Details) - USD ($) $ in Thousands		Dec. 31, 2020	Dec. 31, 2019
Securities, Available-for-sale [Line Items]
Securities, at fair value(1)(2)	[1],[2]	$ 1,514,185	$ 2,449,941
Amortized Cost		$ 1,474,155	$ 2,342,369
Weighted Average
Securities, Available-for-sale [Line Items]
Weighted Average Coupon		3.92%	4.23%
Long
Securities, Available-for-sale [Line Items]
Securities, at fair value(1)(2)		$ 1,514,185	$ 2,449,941
Amortized Cost		$ 1,508,997	$ 2,415,210
Long | Weighted Average
Securities, Available-for-sale [Line Items]
Weighted Average Coupon		3.84%	4.15%
Long | Agency RMBS
Securities, Available-for-sale [Line Items]
Securities, at fair value(1)(2)		$ 911,787	$ 1,901,684
Amortized Cost		$ 881,270	$ 1,886,235
Long | Agency RMBS | Weighted Average
Securities, Available-for-sale [Line Items]
Weighted Average Coupon		3.84%	4.02%
Long | Agency RMBS | Less than three years [Member]
Securities, Available-for-sale [Line Items]
Securities, at fair value(1)(2)		$ 139,059	$ 188,593
Amortized Cost		$ 135,844	$ 187,099
Long | Agency RMBS | Less than three years [Member] | Weighted Average
Securities, Available-for-sale [Line Items]
Weighted Average Coupon		4.15%	3.39%
Long | Agency RMBS | Greater than three years less than seven years [Member]
Securities, Available-for-sale [Line Items]
Securities, at fair value(1)(2)		$ 770,173	$ 961,839
Amortized Cost		$ 742,946	$ 953,031
Long | Agency RMBS | Greater than three years less than seven years [Member] | Weighted Average
Securities, Available-for-sale [Line Items]
Weighted Average Coupon		3.79%	4.25%
Long | Agency RMBS | Greater than seven years less than eleven [Member]
Securities, Available-for-sale [Line Items]
Securities, at fair value(1)(2)		$ 2,555	$ 713,862
Amortized Cost		$ 2,480	$ 708,805
Long | Agency RMBS | Greater than seven years less than eleven [Member] | Weighted Average
Securities, Available-for-sale [Line Items]
Weighted Average Coupon		3.01%	3.89%
Long | Agency RMBS | Greater than eleven year [Member]
Securities, Available-for-sale [Line Items]
Securities, at fair value(1)(2)		$ 0	$ 37,390
Amortized Cost		$ 0	$ 37,300
Long | Agency RMBS | Greater than eleven year [Member] | Weighted Average
Securities, Available-for-sale [Line Items]
Weighted Average Coupon		0.00%	3.51%
Long | Agency RMBS | Interest only securities
Securities, Available-for-sale [Line Items]
Securities, at fair value(1)(2)		$ 47,656	$ 35,279
Amortized Cost		$ 43,406	$ 34,044
Long | Agency RMBS | Interest only securities | Weighted Average
Securities, Available-for-sale [Line Items]
Weighted Average Coupon		3.36%	2.81%
Long | Agency RMBS | Interest only securities | Less than three years [Member]
Securities, Available-for-sale [Line Items]
Securities, at fair value(1)(2)		$ 8,143	$ 9,011
Amortized Cost		$ 7,314	$ 8,611
Long | Agency RMBS | Interest only securities | Less than three years [Member] | Weighted Average
Securities, Available-for-sale [Line Items]
Weighted Average Coupon		3.99%	3.35%
Long | Agency RMBS | Interest only securities | Greater than three years less than seven years [Member]
Securities, Available-for-sale [Line Items]
Securities, at fair value(1)(2)		$ 32,669	$ 25,334
Amortized Cost		$ 29,362	$ 24,512
Long | Agency RMBS | Interest only securities | Greater than three years less than seven years [Member] | Weighted Average
Securities, Available-for-sale [Line Items]
Weighted Average Coupon		3.74%	2.66%
Long | Agency RMBS | Interest only securities | Greater than seven years less than eleven [Member]
Securities, Available-for-sale [Line Items]
Securities, at fair value(1)(2)		$ 5,165	$ 934
Amortized Cost		$ 5,063	$ 921
Long | Agency RMBS | Interest only securities | Greater than seven years less than eleven [Member] | Weighted Average
Securities, Available-for-sale [Line Items]
Weighted Average Coupon		1.04%	1.90%
Long | Agency RMBS | Interest only securities | Greater than eleven year [Member]
Securities, Available-for-sale [Line Items]
Securities, at fair value(1)(2)		$ 1,679	$ 0
Amortized Cost		$ 1,667	$ 0
Long | Agency RMBS | Interest only securities | Greater than eleven year [Member] | Weighted Average
Securities, Available-for-sale [Line Items]
Weighted Average Coupon		0.83%	0.00%
Long | Non-Agency RMBS and CMBS
Securities, Available-for-sale [Line Items]
Securities, at fair value(1)(2)		$ 312,157	$ 283,102
Amortized Cost		$ 317,081	$ 269,124
Long | Non-Agency RMBS and CMBS | Weighted Average
Securities, Available-for-sale [Line Items]
Weighted Average Coupon		2.98%	3.37%
Long | Non-Agency RMBS and CMBS | Less than three years [Member]
Securities, Available-for-sale [Line Items]
Securities, at fair value(1)(2)		$ 58,350	$ 50,120
Amortized Cost		$ 54,339	$ 48,213
Long | Non-Agency RMBS and CMBS | Less than three years [Member] | Weighted Average
Securities, Available-for-sale [Line Items]
Weighted Average Coupon		3.39%	2.73%
Long | Non-Agency RMBS and CMBS | Greater than three years less than seven years [Member]
Securities, Available-for-sale [Line Items]
Securities, at fair value(1)(2)		$ 114,815	$ 87,436
Amortized Cost		$ 109,161	$ 79,326
Long | Non-Agency RMBS and CMBS | Greater than three years less than seven years [Member] | Weighted Average
Securities, Available-for-sale [Line Items]
Weighted Average Coupon		3.45%	4.42%
Long | Non-Agency RMBS and CMBS | Greater than seven years less than eleven [Member]
Securities, Available-for-sale [Line Items]
Securities, at fair value(1)(2)		$ 109,519	$ 127,533
Amortized Cost		$ 123,782	$ 123,924
Long | Non-Agency RMBS and CMBS | Greater than seven years less than eleven [Member] | Weighted Average
Securities, Available-for-sale [Line Items]
Weighted Average Coupon		2.74%	3.31%
Long | Non-Agency RMBS and CMBS | Greater than eleven year [Member]
Securities, Available-for-sale [Line Items]
Securities, at fair value(1)(2)		$ 29,473	$ 18,013
Amortized Cost		$ 29,799	$ 17,661
Long | Non-Agency RMBS and CMBS | Greater than eleven year [Member] | Weighted Average
Securities, Available-for-sale [Line Items]
Weighted Average Coupon		1.46%	0.81%
Long | Non-Agency RMBS
Securities, Available-for-sale [Line Items]
Securities, at fair value(1)(2)		$ 201,090	$ 163,136
Amortized Cost		$ 190,759	$ 151,668
Long | Non-Agency RMBS | Weighted Average
Securities, Available-for-sale [Line Items]
Weighted Average Coupon		3.15%	3.41%
Long | Non-Agency RMBS | Interest only securities
Securities, Available-for-sale [Line Items]
Securities, at fair value(1)(2)		$ 9,610	$ 8,316
Amortized Cost		$ 8,123	$ 6,517
Long | Non-Agency RMBS | Interest only securities | Weighted Average
Securities, Available-for-sale [Line Items]
Weighted Average Coupon		1.17%	1.10%
Long | Non-Agency RMBS | Interest only securities | Less than three years [Member]
Securities, Available-for-sale [Line Items]
Securities, at fair value(1)(2)		$ 5,163	$ 439
Amortized Cost		$ 3,754	$ 401
Long | Non-Agency RMBS | Interest only securities | Less than three years [Member] | Weighted Average
Securities, Available-for-sale [Line Items]
Weighted Average Coupon		0.92%	1.37%
Long | Non-Agency RMBS | Interest only securities | Greater than three years less than seven years [Member]
Securities, Available-for-sale [Line Items]
Securities, at fair value(1)(2)		$ 4,447	$ 7,877
Amortized Cost		$ 4,369	$ 6,116
Long | Non-Agency RMBS | Interest only securities | Greater than three years less than seven years [Member] | Weighted Average
Securities, Available-for-sale [Line Items]
Weighted Average Coupon		1.37%	1.08%
Long | Non-Agency RMBS | Interest only securities | Greater than seven years less than eleven [Member]
Securities, Available-for-sale [Line Items]
Securities, at fair value(1)(2)		$ 0	$ 0
Amortized Cost		$ 0	$ 0
Long | Non-Agency RMBS | Interest only securities | Greater than seven years less than eleven [Member] | Weighted Average
Securities, Available-for-sale [Line Items]
Weighted Average Coupon		0.00%	0.00%
Long | Non-Agency RMBS | Interest only securities | Greater than eleven year [Member]
Securities, Available-for-sale [Line Items]
Securities, at fair value(1)(2)		$ 0	$ 0
Amortized Cost		$ 0	$ 0
Long | Non-Agency RMBS | Interest only securities | Greater than eleven year [Member] | Weighted Average
Securities, Available-for-sale [Line Items]
Weighted Average Coupon		0.00%	0.00%
Long | CLOs And Other Securities [Member]
Securities, Available-for-sale [Line Items]
Securities, at fair value(1)(2)		$ 231,385	$ 220,166
Amortized Cost		$ 257,513	$ 218,048
Long | CLOs And Other Securities [Member] | Weighted Average
Securities, Available-for-sale [Line Items]
Weighted Average Coupon		5.09%	6.60%
Long | CLOs And Other Securities [Member] | Less than three years [Member]
Securities, Available-for-sale [Line Items]
Securities, at fair value(1)(2)		$ 89,235	$ 54,446
Amortized Cost		$ 90,869	$ 54,090
Long | CLOs And Other Securities [Member] | Less than three years [Member] | Weighted Average
Securities, Available-for-sale [Line Items]
Weighted Average Coupon		7.73%	11.11%
Long | CLOs And Other Securities [Member] | Greater than three years less than seven years [Member]
Securities, Available-for-sale [Line Items]
Securities, at fair value(1)(2)		$ 139,830	$ 157,384
Amortized Cost		$ 163,670	$ 155,651
Long | CLOs And Other Securities [Member] | Greater than three years less than seven years [Member] | Weighted Average
Securities, Available-for-sale [Line Items]
Weighted Average Coupon		3.69%	5.38%
Long | CLOs And Other Securities [Member] | Greater than seven years less than eleven [Member]
Securities, Available-for-sale [Line Items]
Securities, at fair value(1)(2)		$ 2,320	$ 8,336
Amortized Cost		$ 2,974	$ 8,307
Long | CLOs And Other Securities [Member] | Greater than seven years less than eleven [Member] | Weighted Average
Securities, Available-for-sale [Line Items]
Weighted Average Coupon		1.14%	0.00%
Long | CLOs And Other Securities [Member] | Greater than eleven year [Member]
Securities, Available-for-sale [Line Items]
Securities, at fair value(1)(2)		$ 0	$ 0
Amortized Cost		$ 0	$ 0
Long | CLOs And Other Securities [Member] | Greater than eleven year [Member] | Weighted Average
Securities, Available-for-sale [Line Items]
Weighted Average Coupon		0.00%	0.00%

[1] Ellington Financial Inc.'s Consolidated Balance Sheet includes assets and liabilities of variable interest entities it has consolidated. See Note 9 for additional details on Ellington Financial Inc.'s consolidated variable interest entities.

[2] Includes assets pledged as collateral to counterparties. See Note 11 for additional details on the Company's borrowings and related collateral.